This invention relates generally to tire-making equipment and relates, more particularly, to apparatus which defines an outer circumference, or circumferential surface, which serves as a forming surface or for grasping the inner surface of a tubular (e.g. tire-shaped) object or for defining an inner circumference for grasping the outer surface of a circular, tubular or round object.
The tire-making equipment with which this invention is to be compared includes belt and tread drums whose outer circumferential surface is capable of expanding and contracting and a transfer ring whose inner circumferential surface is capable of expanding and contracting. In the case of a belt and tread drum, the capacity of the outer circumferential surface to expand and contract accommodates the removal of a completed package from the drum circumference and enables a single drum to be used to form belt and tread drums of alternative diameters. In the case of a transfer ring, the capacity of the inner circumferential surface to expand and contract enables the transfer ring to grasp or release the outer circumference of a belt and tread package when the transfer ring is positioned thereabout.
Conventional designs of the circumferential surfaces of such tire-making equipment involve the use of a plurality of multi-sectional segments disposed about a common centerline and whose outer or inner surfaces collectively define the circumferential surfaces. Preferably, such multi-sectional segments are capable for moving relative to one another during the equipment expansion or contraction process so that the uniformity (i.e. the rounded nature) of the circumferential surface is not appreciably sacrificed. Unless such a uniformity of the circumferential surface is preserved between the expanded and contracted conditions of the equipment, bumps or non-rounded regions which may otherwise be formed about the circumferential surface are likely to contribute to inaccuracies formed within a tire component built upon or engaged by the circumferential surface of the equipment.
The multi-sectional segments of one such design, such as is shown and described in U.S. Pat. No. 5,635,016, includes three sections comprised of an intermediate section and two flanking side sections which are hingedly connected to the intermediate section and which include a plurality of finger members which are moveable into and out of the spacings provided between finger members of a side section of an adjacent segment. Furthermore, the side sections of each segment are interconnected with the respective side sections of the adjacent segments disposed on each side of the segment so that the movement of the segments radially inwardly or outwardly relative to the centerline of the equipment (for the purpose of expanding or contracting the equipment) results in a forced hinged movement of the several respective side sections relative to the intermediate section in a manner which reduces the extent of nonuniformity of the circumferential surface defined by the multi-sectional segments.
However, conventional designs such as that of the referenced patent, do not accommodate an expansion or contraction of the circumferential surface of the equipment through a relatively broad range without appreciably sacrificing the uniformity, or roundness, of the circumferential surface of the equipment.
Accordingly, it is an object of the present invention to provide a new and improved equipment of the aforedescribed class whose circumferential surface can be expanded or contracted through a relatively broad range of diameters without appreciably sacrificing the uniformity of the circumferential surface.
Another object of the present invention is to provide such equipment which is relatively uncomplicated in structure, yet effective in operation.